ha ha ... it's not a pure 2D painting program in fact ...
so yes perhaps hard to recognize : it's 3D coat

Yes 3D coat is scultping,retopo,uv tool, but also great painting tool.
It has a very usefull feature that is Texture Tile making.
You choose the resolution and you can paint on the maps you want : diffuse, normal, specular.
You have :
-layers
-brushes
-masks
-bézier curves, reactangles, paths
-several lighten/Darken tools
-simple blurr (just press Shift when painting)

I forgot , you can indeed paint in 3D on your 3D model and any of the maps (diffuse/Norm/spec).